編譯器錯誤 CS0428
無法將 'Identifier' 方法群組轉換為非委派類型 'type'。 您是否想要叫用方法?
將方法群組轉換為非委派類型時,或嘗試叫用方法但未使用括弧時,就會發生此錯誤。
下列範例會產生 CS0428:
C#
// CS0428.cs
namespace ConsoleApplication1
{
class Program
{
delegate int Del1();
delegate object Del2();
static void Main(string[] args)
{
ExampleClass ec = new ExampleClass();
// The following assignment statement causes compiler error CS0428.
// It attempts to assign the address of Method1 to an integer variable.
// You can only assign the address to an appropriate delegate type.
int i = ec.Method1;
// Del1 is a delegate type that is appropriate for a method like
// Method1 that returns an int. The following assignment statement
// does not cause an error.
Del1 d1 = ec.Method1;
// You can invoke Method1 and assign the int that is returned to
// integer variable i.
i = ec.Method1();
// The following assignment statement causes compiler error CS0428.
// It attempts to assign the address of Method2 to an instance of
// ExampleClass. You can only assign the address to a delegate type.
ec = ExampleClass.Method2;
// Del2 is a delegate type that is appropriate for a method like
// Method2 that returns an instance of a class. The following assignment
// statement does not cause an error.
Del2 d2 = ExampleClass.Method2;
// Similarly, you can invoke Method2 and assign the result returned to ec.
ec = ExampleClass.Method2();
}
}
public class ExampleClass
{
public int Method1() { return 1; }
public static ExampleClass Method2() { return null; }
}
}